Triazole-modified calix[4]crown as a novel fluorescent on-off switchable chemosensor

A novel fluorescent on-off switchable chemosensor 1 with two different types of cationic binding sites is synthesized, which is composed of a triazole-modified calix[4]crown in the 1,3-alternate conformation. Among 15 metal ions examined, the fluorescence of 1 was strongly quenched by Hg2+, Cu2+, Cr3+, and Pb2+; however, the revival of emission from the strongly quenched 1.Pb2+ complex was achievable by the addition of K+, Ba2+, or Zn2+ ions. Thus, metal ion exchange can trigger an on-off switchable fluorescent chemosensor.     

Pyrene excimer-based calix[4]arene FRET chemosensor for mercury(II)

A novel calix[4]arene derivative locked in the 1,3-alternate conformation (2) bearing two pyrene and rhodamine fluorophores was synthesized as a selective sensor for the Hg(2+) ion. The sensoring is based on FRET from pyrene excimer emissions to ring-opened rhodamine absorption upon complexation of the Hg(2+) ion. Addition of Hg(2+) to a mixed solution of 2 gave significantly enhanced fluorescence at ～576 nm via FRET with excitation at 343 nm. We also found that the pyrene excimer emissions formed by the intramolecular π-π interactions are more effective in obtaining strong FRET bands than those by intermolecular π-π interactions.     

Unsymmetrical calix[4]arene bisporphyrin Pacman

[structure: see text] The synthesis of a Pacman heterobisporphyrin associating an octaethyl porphyrinatozinc (ZnOEP) energy donor and a triaryl porphyrinatozinc (ZntPP) energy acceptor around a calix[4]arene spacer is described. Contrary to previous symmetrical architectures, correlations between the chromophores in the unsymmetrical calixarene bisporphyrin Pacman scaffold can now be observed in ROESY experiments. Independent of the excitation wavelength, only the luminescence of the ZntPP moiety was observed corresponding to quenching of the OEP moiety's emission.     

Sensitive fluorescent sensors for malate based on calix[4]arene bearing anthracene

Two chiral fluorescence receptors 3a and 3b based on calix[4]arenes were synthesized, and their chiral recognition properties for enantiomeric malate were studied by fluorescence and ¹H NMR spectra in CHCl₃. The addition of either l- or d-malate caused obvious fluorescence quenching of the host solution. Different fluorescent responses demonstrate that the two receptors have good enantioselective recognition abilities towards malate.     

Supramolecular interaction between water-soluble calix[4]arene and ATP--the catalysis of calix[4]arene for hydrolysis of ATP

The catalysis effect of water-soluble calix[4]arene C[4] (calix[4]arene-5,11,17,23-tetrasulfonate) on hydrolysis of ATP in aqueous solution was studied by HPLC. Using laser photolysis and pulse radiolysis, the supramolecular interaction between water-soluble calix[4]arene and ATP was investigated.     

Aminolysis reaction of calix [ 4 ] arene esters and crystal structures and conformational behaviors of calix[4]arene amides

We first make use of aminolysis of calix[4]arene esters to synthesize calix[4]arene amides. When the two ethyl esters of the calix[4]arene esters are aminolysized, the 1, 3-amide derivative is formed selectively. The crystal structures of the calix-[4]arene with two butyl amide (3b) and four butyl amide moieties (4b) were determined. The intermolecular hydrogen bonds make 4b form two-dimensional net work insolid state. The 1H NMR spectra prove that 3b is of a pinched cone conformation, while 4b and tetraheptylamide-calix[4]arene (6b) take fast interconversion between two C2v isomers in solution and appear an apparent cone conformation at room temperature. As decreasing temperature, the interconversion rate decreases gradually and, finally, the interconversion process is frozen at Tc = -10℃, which makes both conformations of 4b and 6b the pinched cone structures. The hydrogen bond improves the interconversion barrier, and the large different values of the potential barrier between 6b and 4b (or 6b) may     

一种新型杯[4]芳烃的合成

本文通过对特丁基杯[4]芳烃的酚羟基烷基化和苯环特丁基位上的IPSO-硝化制备了一系列对硝基杯[4]芳烃烷基醚,烷基分别是n-C~4H~9(3a)、n-C~8H~1~7(3b)、n-C~1~2H~2~5(3c)和n-C~1~6H~3~3(3d)。^1HNMR表明所有新的杯[4]芳烃都具有锥形(cone)构象。     

A phenanthrene-based calix[4]arene as a fluorescent sensor for Cu and F

A new phenanthrene-based fluorescent calix[4]arene (4) has been synthesized in cone conformation. This compound was examined for its fluorescent properties towards different metal ions (Na⁺, Li⁺, Mg²⁺, Ni²⁺, Ba²⁺, Ca²⁺, Cu²⁺, Pb²⁺) and anions (F⁻, Cl⁻, Br⁻, H₂₄PO⁻,${{\text{H}}_2{\text{PO}}_4}^{-}\text{,}$₃NO⁻,${{\text{NO}}_3}^{-}\text{,}$₄HSO⁻,${{\text{HSO}}_4}^{-}\text{,}$ CH₃COO⁻) by fluorescence spectroscopy. The properties of the compound were evaluated and show that it is a fluorescence sensor for Cu²⁺ and F⁻. With the addition of Cu²⁺ and F⁻, the fluorescence was severely quenched.     

A novel calix[4]arene fluorescent receptor for selective recognition of acetate anion

A novel bridged fluorescent calix[4]arene with 1,8-diaminoanthracene and glycine at the upper rim has been prepared, which exhibited selective recognition towards AcO⁻ over other anions such as F⁻, Cl⁻, Br⁻, , , I⁻ and by fluorescence spectroscopy and ¹H NMR method.     

Synthesis of a novel fluorescent anthryl calix[4]arene as picric acid sensor

A novel and sensitive fluorescence sensor has been designed by click chemistry. Based on the obvious and selective fluorescence quenching of anthryl calix[4]arene, a sensitive and robust platform were developed for visual detection of picric acid (TNP) in the mixture of nitro aromatics. The computational calculations revealed the formation of host–guest complex driven by π–π stacking interactions.     

Bifunctional fluorescent calix[4]arene chemosensor for both a cation and an anion

[reaction: see text] A new fluorogenic cone calix[4]triazacrown-5 (1) bearing two pyrene amide groups and its structural analogue 2 have been prepared. Excited at 343 nm, 1 and 2 reveal excimer emissions at 448 and 472 nm, respectively. When heavy metal ions such as Pb(2+) and Co(2+) are bound to 1, the fluorescence intensities of both monomer and excimer are quenched whereas H bonding-assisted F(-) binding to 1 gives rise to a quenched monomer emission with little excimer emission change.     

Highly selective fluorescent sensing of Pb by a new calix[4]arene derivative

A new chemosensor was synthesized by the alkylation of p-tert-butyl-calix[4]arene with three N,N-diethylacetamide groups and one methyl 3-ethoxy-naphthalene-2-carboxylate, which exhibited highly selective fluorescent response to Pb²⁺ over alkali, alkali earth metal ions and some transition metal ions in CH₃CN-H₂O.     

Nanoencapsulation of calix[4]arene inclusion complexes

A hexameric resorcinarene nanocapsule in wet CDCl3 forms inclusion complexes of calix[4]arene with tetramethylammonium and trimethylsulfoxonium cations to give highly stable Russian-doll-type multicomponent assemblies. The 2D NOESY experiments revealed the size of the assembly, the close proximity of the encapsulated calix[4]arene molecule to the resorcinarene molecules of the capsule, and the inclusion of the tetramethylammonium cation in the calix[4]arene cavity.     

Study on thermal decomposition of calix[6]arene and calix[8]arene

Thermal decomposition kinetics of calix[6]arene (C6) and calix[8]arene (C8) were studied by Thermogravimetry analysis (TG) and Differential thermal analysis (DTA). TG was done under static air atmosphere with dynamic heating rates of 1.0, 2.5, 5.0, and 10.0 K min⁻¹. Model-free methods such as Friedman and Ozawa–Flynn–Wall were used to evaluate the kinetic parameters such as activation energy (E _a) and pre-exponential factors (ln A). Model-fitting method such as linear regression was used for the evaluation of optimum kinetic triplets. The kinetic parameters obtained are comparable with both the model-free and model-fitting methods. Within the tested models, the thermal decomposition of C6 and C8 are best described by a three dimensional Jander’s type diffusion. The antioxidant efficiency of C6 and C8 was tested for the decomposition of polypropylene (PP).     

Highly selective fluorescent chemosensor for Na~+ based on pyrene-modified calix[4]arene derivative

A novel calix[4]arene derivative with pyrene fluorophores at the upper rim and tetraester ionophores at the lower rim was synthesized in six steps,and its structure was proved by NMR and ESI-MS spectro-scopies. Furthermore,the chemosensing behavior of the host compound for alkali and alkaline earth metal ions was investigated by fluorescence spectroscopy. The obtained results show that the calix-arene host can selectively bind sodium ion with the complexation stability constant of 2190 mol-1.L. The complexa...     

Highly selective fluorescent sensing of Cu ion by an arylisoxazole modified calix[4]arene

A novel fluorescent chemosensor 1 with two anthraceneisoxazolymethyl groups at the lower rim of calix[4]arene has been synthesized, which revealed a dual emission (monomer and excimer) when excited at 375 nm. This chemosensor displayed a selective fluorescence quenching only with Cu²⁺ ion over all other metal ions examined. When Cu²⁺ ion was bound to 1, the fluorescence intensities of both monomer and excimer were quenched. Furthermore, the association constant for the 1:1 complex of 1·Cu²⁺ was determined to be (1.58 ± 0.03) × 10⁴ M⁻¹.     

A new fluorescent double-cavity calix[4]arene: synthesis and complexation studies toward nitroanilines

A novel bicyclic calix[4]arene (4) molecular receptor has been synthesized, and its sensory abilities toward noxious aromatic nitroamines evaluated in apolar media. Molecular host–guest interactions examined through fluorescence and ¹H NMR spectroscopies showed the formation of 1:1 type endo-inclusion complexes with all the nitroaniline guests. The potential of 4 as a chemical sensor is established.     

Liquid crystalline behavior and fluorescent property of calix[4]arene containing azobenzene photochromic group

The reaction of 4′-hydroxy-4-methyl azobenzene (1) and 1,6-dibromohexane afforded 6-bromo-1-((4-((4-met hylphenyl)azo)phenyl)oxy)hexane (2), which further reacted with p-tert-butylcalix[4]arene to give the calix[4]arene derivative (3) whose lower rim had been modified by the azobenzene photochromic group. The structure of 3 was characterized by ¹H-nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS). The fluorescence intensity of compound 3 was two to four times higher than that of compounds 1 and 2 as the azobenzene group concentration in the range of 1.6 × 10⁻⁵ to 8.0 × 10⁻⁴ mol/L, indicating that the fluorescence quantum yield of the azobenzene group had been improved through being attached to the calix[4]arene skeleton. The liquid crystalline behavior of compound 3 was studied by polarized microscopy (POM) and differential scan calorimeter (DSC). Compound 3 exhibited the enchased texture of a smectic liquid crystal from 209.4°C to 219.5°C on heating, while 2 exhibited a liquid crystalline phase from 87.4 to 83.2°C on cooling. It was found that the calix[4]arene skeleton was a good platform for conformation immobilization of azobenzene photochromic group and the formation of liquid crystalline. Translated from Chinese Journal of Applied Chemistry, 2006, 23(9): 1023–1026 [译自: 应用化学]